Occultation event with (5144) Achates, event index number 1736
Regions able to see the event: Europe
Geocentric closest approach at 2025/12/30 21:42:19 UTC
J2000 position of star is 02:50:57.3 +26:58:28
Equinox of date position of star is 02:52:29.3 +27:04:50
Star is 6 degrees from the moon. Moon is 83% illuminated.
Stellar brightness G=16.8, apparent brightess of occulting body is G=14.8
Use an exposure time of 2.00 seconds with the standard RECON-QHY system.
SNR of 3.2 per integration for unocculted signal
Expected flux drop is 14% with SNR of 0.4 for the occulted depth (per occulted point)
Apparent velocity is 8.2 km/sec on the sky relative to the star, or, 8.2 arcsec/hr.
Position angle of asteroid motion is 43.4 degrees
The recommended exposure time corresponds to 16.4 km per image.
The 1-sigma error in the time of the event is 3.3 seconds.
The 1-sigma cross-track error in the shadow position is 12.7 km.
The sky-plane scale is 3572.8 km/arcsec.
Diameter estimates:
87.5 km assuming a 5% albedo, aximum of 10.7 sec for a central chord
35.7 km assuming a 30% albedo, maximum of 4.4 sec for a central chord
Cross-track diameter of 81.0 km used for deployment plan.
Star training set for 5144_Achates, (2025/12/30 21:42UT) Object RA Dec mag sep mel Aldebaran 04:37:24.9 +16:33:34 0.8 26.45 22 Hamal 02:08:38.7 +23:35:03 2.0 10.50 14 35 Ari 02:44:59.1 +27:48:58 4.7 1.82 7 PPM 092026 02:53:23.0 +27:22:46 8.0 0.36 6 PPM 092008 02:51:21.4 +27:12:52 9.4 0.29 6 5144_Achates 02:52:29.3 +27:04:50 14.8 6 Positions are for equinox of date
Star training set for 5144_Achates, (2025/12/30 21:42UT) Object RA Dec mag sep mel Aldebaran 04:35:55.4 +16:30:29 0.8 26.45 22 Hamal 02:07:10.8 +23:27:41 2.0 10.50 14 35 Ari 02:43:27.1 +27:42:25 4.7 1.82 7 PPM 092026 02:51:50.7 +27:16:25 8.0 0.36 6 PPM 092008 02:49:49.4 +27:06:29 9.4 0.29 6 5144_Achates 02:50:57.3 +26:58:28 14.8 6 Positions are for J2000